The award-winning author of A Trouble of Fools rekindles her 61 redheaded female private eye, Carlotta Carlyle, in a rivetingly well-told story. Her old friend, Lieutenant Mooney of the Boston police, is under investigation for excessive brutality and Carlyle is trying to track down the lone witness who can clear his name, a blonde hooker with a snake tattoo. While on surveillance in Boston's Combat Zone, Carlyle (who drives a cab to make ends meet) accidentally gets a fare and a second case; a troubled teenage boy, freshly rolled for his wallet, tumbles into her cab and involves her in his search for a missing classmate. The boy's case takes Carlyle to the Emerson School, a mini-Harvard prep school, whose putting-green grass and stately buildings seem worlds removed from the Combat Zone's alleys and three-story flophouses. But after she discovers the body of Emerson's drama teacher, Carlyle realizes the spotless image is a facade. There are surprises at the finish, made all the more potent by the novel's unforced paced and charm. Mystery Guild main selection. (Mar.)